1. Field of the Invention
The present invention relates to a continuous casting mold.
2. Description of the Prior Art
The continuous casting molds known to the art, whether configured as multi-station molds such as, for example, the xe2x80x9ctwin rollerxe2x80x9d pursuant to a 19th Century Bessemer patent, or as a single-station mold, are comprised of a copper wall, which is cooled from the back with water via a water distribution chamber.
The state of the art and its shortcomings (as depicted in FIG. 1), are illustrated in the following using the example of an oscillating single-station mold (1), whereby preferably steel using a SEN or submerged entry nozzle (2) and casting powder (3) or casting slag (3.1) is cast into slabs or ingots having a thickness of between 150 and 30 mm and a maximum width of up to of 3.300 mm at a casting velocity (4) of up to max. 15 m/min.
Conventionally, such a mold is supplied with water cooling of, for example, 4,000-8,000 L/min with a strand [casting] width (5) of 1,600 mm and at a pressure of between 5-15 bar, whereby said water cooling is constructed in such a manner that the water temperature TMin at the mold inlet (6) is held constant independent of
casting velocity (4),
casting width (5),
thickness of the copper plate (7),
casting powder (3),
casting slag (3.1),
water pressure (9) and
oscillation (12).
As casting velocity increases, the mold coolant water (10) accrues a higher temperature TMout (11). The temperature difference (13) between the constant inlet temperature (16) and the variable outlet temperature (11) is a function of the aforementioned constraints. If, for example, the system is considered under the assumption that all constraints, save for casting velocity, are held constant, then, with increasing casting velocity from VC1 (4.1) to VC2 (4.2) the outlet temperature (11) or the temperature difference (13) and consequently the mold skin temperature (14), increases from T1 (14.1) to T2 (14.2) as does the energy under the energy lobe [sic] (15) from (15.1) to (15.2).
Consequently, with changing casting velocity (4) and with the variation in the aforementioned constraints, the xe2x80x98hot-facexe2x80x99 temperature (14) changes, resulting in constantly varying lubrication of the strand shell (16) and thermal flux (17) in the mold, whereby said variations in casting conditions result in perturbations of the casting process and in the surface of the strand.
Continuing with the description of the water circuit, the water then is cooled to a desired constant inlet temperature (6) in an output controllable heat exchanger (18) and the water is re-directed to the mold under a preset pressure (9) with the aid of a pump station (19). Moreover, at high casting velocities of 10-15 m/min, said water cooling system runs the risk of forming vapor films at the xe2x80x98cold facexe2x80x99 of the mold shell (20), because the vapor point at a preset pressure is exceeded the over-temperature in the thermal transfer region of the copper wall.
The heat exchanger (18) is cooled via a cooling tower (21) equipped with a pump station (21.1).
The object of the invention is to create a generic process and device which improve upon the mold operation and the continuous casting process.
The unanticipated solution that is not obvious to one skilled in the art is made clear by the characteristics. Pursuant to the invention, a mold cooling system is achieved in which the mold skin temperature xe2x80x98hot facexe2x80x99 (14) remains constant under varying casting conditions and is maintained under control whereby constant conditions are established for the casting powder (3) and the casting slag (3.1) wherein an unperturbed thermal flux (17) is assured over the width of the casting without the formation of a vapor layer (Leidenfrost effect).